IP telephony, also known as voice over IP or VoIP, has become a key driver in the evolution of voice communications. VoIP technology is useful not only for phones, but also as a broad application platform enabling voice interactions on devices such as PCs, mobile handhelds and many other devices where voice communication is an important feature. Several VoIP service providers, such as Skype® and Vonage®, now provide VoIP communications services globally.
In order to technically accommodate the growing number of telephone users around the world, and increased interest in Internet telephony, the International Telecommunications Union (ITU) has adopted a number of protocols to facilitate communications. One such protocol is E.164, which provides a uniform means for identifying any telephone number in the world to any telephony user in the world. This protocol operates for standard public switched telephone networks (PSTNs). Additionally, a standard referred to as Electronic Numbering, or ENUM, has been adopted which uses the domain name system (DNS) to map E.164 formatted telephone numbers to Web addresses or uniform resource locators, thereby effectively enabling the E.164 protocol to be used for IP telephony.
The international E.164 protocol has a standard format for telephone numbers. An E.164 formatted number has at most 15 digits, and contains an E.164 prefix (which is typically a “+” sign), a country code, and a subscriber telephone number. In North America, the subscriber telephone number may for example consist of an area code and a seven digit telephone number.
When making telephone calls via a traditional PSTN, a subscriber is able to enter abbreviated numbers for local and national telephone calls. For example, for a local call in the United States, a user may simply enter the seven digit telephone number without an E.164 prefix, the country code or the area code. Local and national calls are possible with PSTN systems because the fixed-line phones from which such calls are made are hardwired directly to the local PSTN center.
By contrast, there is no such concept of local, long distance or national calls when making a call via Internet telephony. VoIP calls use the Internet, which is world-wide and not tied to any single location. While a VoIP call may be made between two local points, that call may be routed through servers located across the globe. Consequently, existing global VoIP service providers require users to enter fully formatted E.164 telephone numbers. Even when making a local call, within for example the United States, instead of simply entering the seven digit telephone number, the VoIP subscriber must enter “+,” then the country code, then the area code, then the telephone number. This is time consuming and bothersome, especially when subscribers are used to the concept of abbreviated telephone numbers for local and national calls with traditional PSTN systems.